Lumia 800 battery

My battery life has plummited these last few weeks. Its not something I noticed before I got the 7.8 update. I have run the diagnostic thing and the battery output is only 3.2V and 400mah fully charged I read online that its meant to be 1000mah ! Do I need a new battery ? Id there an upgrade and why the hell does the lumia only charge with the phone on ! I'm sure this is the cause of my battery damage

I was always taught that a battery that is in use while charging is bad. As it charges and discharges at the same time. When a battery isn't fully discharged before being recharged it doesn't quite recharge to 100%. Over time a battery under these circumstances that claims to be at 100% is actually at 70% for instance. Ita the reasons your instructions for your laptop says do not use while charging battery. It isn't normal phone behaviour I haven't seen any other phone charge like this.

I was always taught that a battery that is in use while charging is bad. As it charges and discharges at the same time. When a battery isn't fully discharged before being recharged it doesn't quite recharge to 100%. Over time a battery under these circumstances that claims to be at 100% is actually at 70% for instance. Ita the reasons your instructions for your laptop says do not use while charging battery. It isn't normal phone behaviour I haven't seen any other phone charge like this.

Wasn't this true only for Li batteries. These new ones being hybrids don't need a full discharge, else you lose battery cells?